Scaling method for a digital photolithography system

ABSTRACT

A method for scaling a pixel location in a digital photolithography system by rotating a pixel panel is provided. The method determines the angle of rotation of the pixel panel relative to a subject and calculates the original location of the pixel to be scaled. The method calculates the desired location of the pixel and determines the angle through which the pixel panel should be rotated to align the pixel with the desired location in a first dimension. The scan rate of the pixel panel and the subject is altered to align the pixel with the desired location in a second dimension.

CROSS REFERENCE

[0001] This patent is a continuation-in-part of U.S. patent Ser. No.09/712,730 filed Nov. 14, 2000, which is hereby incorporated byreference.

BACKGROUND

[0002] The present invention relates generally to lithographic exposureequipment, and more particularly, to a photolithography system andmethod, such as can be used in the manufacture of semiconductorintegrated circuit devices.

[0003] In conventional analog photolithography systems, the photographicequipment requires a mask for printing an image onto a subject. Thesubject may include, for example, a photo resist coated semiconductorsubstrate for manufacture of integrated circuits, metal substrate foretched lead frame manufacture, conductive plate for printed circuitboard manufacture, or the like. A patterned mask or photomask mayinclude, for example, a plurality of lines or structures. During aphotolithographic exposure, the subject must be aligned to the mask veryaccurately using some form of mechanical control and sophisticatedalignment mechanism.

[0004] U.S. Pat. No. 5,691,541, which is hereby incorporated byreference, describes a digital, reticle-free photolithography system.The digital system employs a pulsed or strobed excimer laser to reflectlight off a pixel panel (e.g., a programmable digital mirror device, or“DMD”) for projecting an image (e.g., a line or pattern) onto a subject(e.g., a wafer, printed circuit board, textile, flexible member). Thesubject is mounted on a stage that is moves during the sequence ofpulses.

[0005] The above-described digital photolithography system projects apixel-mask pattern onto a subject such as a wafer, printed circuitboard, or other medium. The component image consists of a plurality ofpixel elements, corresponding to a pixel pattern provided to the pixelpanel. As a result, light can be projected onto or through the pixelpanel to expose the plurality of pixel elements on the subject, and thepixel elements can be moved and altered, according to the pixel-maskpattern, to create contiguous images on the subject.

[0006] Certain improvements are desired for digital photolithographsystems, such as the ones described above. For one, it is desirable toaccommodate a desired change in the scale of the images being exposed.For example, if the subject were a textile, the image may need to expandand/or contract to accommodate the flexibility in the textile. Inanother example, it may be desirable to scale the image for otherreasons.

SUMMARY

[0007] A technical advance is provided by a novel method and system forscaling a pixel element on a subject. In one embodiment, the subject ispositioned in a first plane and the method comprises providing a pixelpanel to generate the pixel element, where the pixel panel is positionedin a second plane substantially parallel to the first plane. A firstscan rate is determined, and an original focal point of the pixelelement on the subject is determined. A scaled focal point is calculatedfor the pixel element on the subject, where the scaled focal pointincludes a first coordinate in a first dimension and a second coordinatein a second dimension. The pixel panel is rotated relative to thesubject to position the pixel element at the first coordinate in rotatedrelative to the subject to position the pixel element at the firstcoordinate in the first dimension of the scaled focal point, and thefirst scan rate is altered to a second scan rate to position the pixelelement at the second coordinate in the second dimension of the scaledfocal point.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a block diagram of an improved digital photolithographysystem for implementing various embodiments of the present invention.

[0009]FIGS. 2 and 3 illustrate various overlay arrangement of pixelsbeing exposed on a subject.

[0010]FIGS. 4 and 5 illustrate the effect of overlaid pixels on thesubject.

[0011]FIG. 6 illustrates a component exposure from the system of FIG. 1,compared to conventional exposures from the systems of FIGS. 1b and 1 a.

[0012]FIG. 7 illustrates various pixel patterns being provided to apixel panel of the system of FIG. 1.

[0013]FIGS. 8, 9, and 10.1-10.20 provide diagrams of a subject that ispositioned and scanned at an angle on a stage. The angle facilitates theoverlapping exposure of a site on the subject according to oneembodiment of the present invention.

[0014]FIG. 11 is a block diagram of a portion of the digitalphotolithography system of FIG. 1 for implementing additionalembodiments of the present invention.

[0015] FIGS. 12-13 provide diagrams of a subject that is positioned andscanned at an angle on a stage and being exposed by the system of FIG.11.

[0016]FIG. 14 illustrates a site that has been overlapping exposed 600times.

[0017]FIG. 15 illustrates a pixel that is to be horizontally scaled by apixel panel rotatably aligned with a subject.

[0018]FIG. 16 is a flow chart illustrating a method for scaling a pixel.

[0019]FIG. 17a illustrates a pixel that is to be horizontally scaled byrotating a pixel panel with respect to a subject.

[0020]FIG. 17b illustrates an enlarged view of the area within thedashed line of FIG. 17a.

[0021]FIG. 18 illustrates a subject containing a pixel location that isinaccessible to a pixel panel as aligned with the subject.

[0022]FIG. 19 illustrates the pixel panel of FIG. 18 after being rotatedto access the pixel location.

DETAILED DESCRIPTION

[0023] The present disclosure relates to exposure systems, such as canbe used in semiconductor photolithographic processing. It is understood,however, that the following disclosure provides many differentembodiments, or examples, for implementing different features of theinvention. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to limit the invention fromthat described in the claims.

[0024] Maskless Photolithography System

[0025] Referring now to FIG. 1, a maskless photolithography system 30includes a light source 32, a first lens system 34, a computer aidedpattern design system 36, a pixel panel 38, a panel alignment stage 39,a second lens system 40, a subject 42, and a subject stage 44. For thesake of example, the subject 42 may be a semiconductor wafer with aresist layer or coating 46 disposed thereon. The light source 32 may bean incoherent light source (e.g., a Mercury lamp) that provides acollimated beam of light 48 which is projected through the first lenssystem 34 and onto the pixel panel 38.

[0026] The pixel panel 38 is provided with digital data via suitablesignal line(s) 50 from the computer aided pattern design system 36 tocreate a desired pixel pattern (the pixel-mask pattern). The pixel-maskpattern may be available and resident at the pixel panel 38 for adesired, specific duration. Light emanating from (or through) thepixel-mask pattern of the pixel panel 38 then passes through the secondlens system 40 and onto the subject 42. In this manner, a pixel image isprojected onto the resist coating 46 of the subject 42.

[0027] The computer aided mask design system 36 can be used for thecreation of the digital data for the pixel-mask pattern. The computeraided pattern design system 36 may include computer aided design (CAD)software similar to that which is currently used for the creation ofmask data for use in the manufacture of a conventional printed mask. Anymodifications and/or changes required in the pixel-mask pattern can bemade using the computer aided pattern design system 36. Therefore, anygiven pixel-mask pattern can be changed, as needed, almost instantlywith the use of an appropriate instruction from the computer aidedpattern design system 36. The computer aided mask design system 36 canalso be used for adjusting a scale of the image or for correcting imagedistortion.

[0028] In the present embodiment, the pixel panel 38 is a digital lightprocessor (DLP) or digital mirror device (DMD) such as is illustrated inU.S. Pat. No. 5,079,544 and patents referenced therein. Current DMDtechnology provides a 600×800 array of mirrors for a set of potentialpixel elements. Each mirror can selectively direct the light 48 towardsthe subject 42 (the “ON” state) or away from the subject (the “OFF”state). Furthermore, each mirror can alternate between ON and OFF forspecific periods of time to accommodate variations in light efficiency.For example, if the second lens system 40 has a “darker” area (e.g., aportion of the lens system is inefficient or deformed), the DMD canalternate the mirrors corresponding with the “brighter” areas of thelens, thereby equalizing the overall light energy projected through thelens. For the sake of simplicity and clarity, the pixel panel 38 will befurther illustrated as one DMD. Alternate embodiments may use multipleDMDs, one or more liquid crystal displays and/or other types of digitalpanels.

[0029] In some embodiments, the computer aided mask design system 36 isconnected to a first motor 52 for moving the stage 44, and a driver 54for providing digital data to the pixel panel 38. In some embodiments,an additional motor 55 may be included for moving the pixel panel, asdiscussed below. The system 36 can thereby control the data provided tothe pixel panel 38 in conjunction with the relative movement between thepixel panel 38 and the subject 42.

[0030] Pixel Overlay

[0031] In some embodiments, the amount of exposure time, or exposureintensity, of light from the pixel panel 38 directly affects the resistcoating 46. For example, if a single pixel from the pixel panel 38 isexposed for a maximum amount of time onto a single site of the subject42, or for a maximum intensity, then the corresponding portion of resistcoating 46 on the subject would have a maximum thickness (afternon-exposed or under exposed resist has been removed). If the singlepixel from the pixel panel 38 is exposed for less than the maximumamount of time, or at a reduced intensity, the corresponding portion ofresist coating 46 on the subject 42 would have a moderate thickness. Ifthe single pixel from the pixel panel 38 is not exposed, then thecorresponding portion of resist coating 42 on the subject 42 wouldeventually be removed.

[0032] Referring now to FIGS. 2 and 3, it is desired that each pixelelement exposed onto a site overlap previous pixel element exposures.FIG. 2 shows a one-direction overlay scenario where a pixel element 80.1is overlapped by pixel element 80.2, which is overlapped by pixelelement 80.3, . . . which is overlapped by pixel element 80.N, where “N”is the total number of overlapped pixel elements in a single direction.It is noted that, in the present example, pixel element 80.1 does notoverlay pixel element 80.N.

[0033]FIG. 3 is a two-dimensional expansion FIG. 2. In this example,pixel element 80.1 is overlapped in another direction by pixel element81.1, which is overlapped by pixel element 82.1, . . . which isoverlapped by pixel element 8M.N, where “M” is the total number ofoverlapped pixel elements in a second direction. As a result, a total ofM×N pixel elements can be exposed for a single site.

[0034] Referring now to FIG. 4, consider for example a site that has thepotential to be exposed by (M,N)=(4,4) pixel elements. In this example,only four of the 16 possible pixel elements are actually “ON”, andtherefore expose portions of the subject 42. These four pixel elementsare designated: 100.1, 100.2, 100.3, 100.4. The four pixel elements100.1-100.4 are exposed onto the photo resist 46 of the subject 42. Allfour pixel elements 100.1-100.4 overlap with each other at an area 102;three of the pixel elements overlap at an area 104; two of the pixelelements overlap at an area 106; and an area 108 is only exposed by onepixel element. Accordingly, area 102 will receive maximum exposure(100%); area 104 will receive 75% exposure; area 106 will receive 50%exposure; and area 108 will receive 25% exposure. It is noted that thearea 102 is very small, {fraction (1/16)}th the size of any pixelelement 100.1-100.4 in the present example.

[0035] Referring now to FIG. 5, the example of FIG. 4 can be expanded to(M,N)=(6,6) pixel elements, with two more overlapping pixel elements100.5, 100.6 in the ON state. The pixel elements 100.5, 100.6 aretherefore exposed onto the photo resist 46 of the subject 42 so thatthey overlap some of the four pixel elements 100.1-100.4. In thisexpanded example, the pixel elements 100.1-100.4 overlap with each otherat area 102; the four pixel elements 100.2-100.5 overlap each other atan area 110; and the four pixel elements 100.3-100.6 overlap each otherat an area 112. In addition, area 114 will receive 75% exposure; area116 will receive 50% exposure; and area 118 will receive 25% exposure.As a result, a very small ridge is formed on the photo resist 46.

[0036] In one embodiment, the pixel panel 32 of the present inventionmay have a 600×800 array of pixel elements. The overlapping is definedby the two variables: (M, N). Considering one row of 600 pixels, thesystem overlaps the 600 pixels onto an overlay area 184 of:

(M,N)=20 pixels×30 pixels.   (1)

[0037] Referring also to FIG. 6, the process of FIGS. 4 and 5 can berepeated to produce a diagonal component 120 on the subject 42. Althoughthe example of FIGS. 4 and 5 have only four potential degrees ofexposure (100%, 75%, 50%, 25%), by increasing the number of overlaps(such as is illustrated in FIG. 3), it is possible to have a very fineresolution of desired exposure.

[0038] The diagonal component 120 appears as a prism-shaped structurehaving a triangular cross-section. If the subject 42 is a wafer, thecomponent 120 may be a conductor (e.g., a metal line), a section ofpoly, or any other structure. The top most portion 120 t of thecomponent is the portion of photo resist 46 that is overlapped the mostby corresponding pixel elements, and therefore received the maximumexposure.

[0039] Overlay Methods

[0040] Referring again to FIG. 1, the above-described overlays can beimplemented by various systems and methods. In general, variouscombinations of moving and/or arranging the pixel panel 38 and/or thesubject 42 can achieve the desired overlap.

[0041] In one embodiment, the maskless photolithography system 30performs two-dimensional digital scanning by rapidly moving the imagerelative to the subject in two directions (in addition to the scanningmotion). The panel motor 55 is attached to the pixel panel 38 to movethe pixel panel in two directions, represented by an x-arrow 132 and ay-arrow 134. The panel motor 55 may be a piezo electric device (PZT)capable of making very small and precise movements.

[0042] In addition, the scanning motor 55 scans the stage 44, and hencethe subject 42, in a direction 136. Alternatively, the stage 44 can befixed and the panel motor 55 can scan the pixel panel 38 (and the lenses40) opposite to direction 136.

[0043] Referring also to FIG. 7, corresponding to the image scanningdescribed above, the pixel-mask pattern being projected by the pixelpanel 38 changes accordingly. This correspondence can be provided, inone embodiment, by having the computer system 36 (FIG. 1) control boththe scanning movement 70 and the data provided to the pixel panel 38.The illustrations of FIG. 7 and the following discussions describe howthe data can be timely provided to the pixel panel.

[0044]FIG. 7 shows three intermediate patterns of pixel panel 38. Sincethe pattern on the pixel panel 38 and the data on the signal lines 50change over time, the corresponding patterns on the pixel panel and dataon the signal lines at a specific point in time are designated with asuffix “0.1”, “0.2”, or “0.3”. In the first intermediate pattern, thepattern of pixel panel 38.1 is created responsive to receiving data D0provided through the signal lines 50.1. In the present example, thepattern is created as a matrix of pixel elements in the pixel panel38.1. After a predetermined period of time (e.g., due to exposureconsiderations being met), the pattern is shifted. The shifted pattern(now shown as pixel panel 38.2) includes additional data D1 providedthrough the signal lines 38.2. The shifting between patterns may alsoutilize a strobing or shuttering of the light source 32.

[0045] In the second intermediate pattern of FIG. 7, D1 represents theleft-most column of pixel elements in the pattern of DMD 38.2. Afteranother predetermined period of time, the pattern (now shown as pixelpanel 38.3) is shifted again. The twice-shifted pattern includesadditional data D2 provided through the signal lines 38.2. In the thirdintermediate pattern of FIG. 7, D2 now represents the left-most columnof pixel elements in the pattern of the DMD 38.3. Thus, the patternmoves across the pixel panel 38 in a direction 138. It is noted that thepattern direction 138, as it is being provided to the pixel panel 38from the signal lines 50, is moving opposite to the scanning direction136. In some embodiments, the pattern may be shifted in additionaldirections, such as perpendicular to the scanning direction 136.

[0046] Referring now to FIG. 8, in some embodiments, the masklessphotolithography system 30 performs two-dimensional digital scanning byrapidly moving the image relative to the subject 42 in one direction (inaddition to the scanning motion) while the subject is positioned on thestage 44 to accommodate the other direction. The panel motor 55 movesthe pixel panel 38 in one direction, represented by the y-arrow 134. Thescanning motor 55 scans the stage 44, and hence the subject 42 in adirection 136. Alternatively, the stage 44 can be fixed and the panelmotor 55 can scan the pixel panel 38 (and the lenses 40) opposite todirection 136.

[0047] The image from the pixel panel 38 and/or the subject 42 isaligned at an angle θ with the scan direction 136. Considering that eachpixel projected onto subject 42 has a length of l and a width of w, thenθ can be determined as: $\begin{matrix}{\theta = {\tan^{- 1}\left( \frac{w - {1/M}}{N \times l} \right)}} & (2)\end{matrix}$

[0048] In another embodiment, the offset may go in the oppositedirection, so that θ can be determined as: $\begin{matrix}{\theta = {\tan^{- 1}\left( \frac{w + {1/M}}{N \times l} \right)}} & (3)\end{matrix}$

[0049] Referring to FIGS. 9 and 10.1, consider for example two sites140.1, 142.1 on the subject 42. Initially, the two sites 140.1 and 142.1are simultaneously exposed by pixel elements P1 and P50, respectively,of the pixel panel 38. The pixel elements P1 and P50 are located at arow R0 and columns C1 and C0, respectively, of the pixel panel 38. Thisrow and column designation is arbitrary, and has been identified in thepresent embodiment to clarify the example. The following discussion willfocus primarily on site 140.1. It is understood, however, that themethods discussed herein are typically applied to multiple sites of thesubject, including the site 142.1, but further illustrations anddiscussions with respect to site 142.1 will be avoided for the sake ofclarity.

[0050] As can be clearly seen in FIG. 9, the pixel panel 38 is angledwith respect to the subject 42 and the scan direction 136. As the system30 scans, pixel element P11 would normally be projected directly on topof site 140.1. However, as shown in FIG. 10.2, the pixel element P11exposes at a location 140.11 that is slightly offset in the y direction(or −y direction) from the site 140.1. As the system 30 continues toscan, pixel elements P12-P14 are exposed on offset locations140.12-140.14, respectively, shown in FIGS. 10.3-10.5, respectively.Pixel elements P11-P14 are on adjacent consecutive rows R1, R2, R3, R4of column C1 of the pixel panel 38.

[0051] In the present embodiment, the scanning motor 52 moves the stage44 (and hence the subject 42) a distance of l, the length of the pixelsite 140.1, for each projection. To provide the offset discussed above,the panel motor 55 moves the pixel panel 38 an additional distance ofl/(N−1) for each projection. (N=5 in the present example). Therefore, atotal relative movement SCAN STEP for each projection is:

SCAN STEP=l+l/(N−1).   (4)

[0052] In another embodiment, the offset may go in the oppositedirection, so that the total relative movement SCAN STEP for eachprojection is:

SCAN STEP=l−l/(N−1).   (5)

[0053] In some embodiments, the panel motor 55 is not needed. Instead,the scanning motor 52 moves the stage the appropriate length (equation 4or 5, above).

[0054] Once N locations have been exposed, the next pixel elements beingprojected onto the desired locations are of an adjacent column. Withreference to FIG. 10.6, in the present example, a pixel element P2 atrow R5, column C2 exposes a location 140.2 that is slightly offset inthe x direction (or −x direction, depending on whether equation 4 or 5is used) from the site 140.1. As the system 30 continues to scan, pixelelements P21-P24 are exposed on offset locations 140.21-140.24,respectively, shown in FIGS. 10.7-10.10, respectively. Pixel elementsP21-P24 are on adjacent consecutive rows R6, R7, R8, R9 of column C2 ofthe pixel panel 38.

[0055] Once N more pixel locations have been exposed, the next pixelelements being projected onto the desired locations are of yet anotheradjacent column. With reference to FIG. 10.11, in the present example, apixel element P3 at row R10, column C3 exposes a location 140.3 that isslightly offset in the x direction (or −x direction, depending onwhether equation 4 or 5 is used) from the location 140.2. As the system30 continues to scan, pixel elements P31-P34 are exposed on offsetlocations 140.31-140.34, respectively, shown in FIGS. 10.12-10.15,respectively. Pixel elements P31-P34 are on adjacent consecutive rowsR11, R12, R13, R14 of column C3 of the pixel panel 38.

[0056] The above process repeats to fully scan the desired overlappedimage. With reference to FIG. 10.16, in the present example, a pixelelement P4 at row R15, column C4 exposes a location 140.4 that isslightly offset in the x direction (or −x direction, depending onwhether equation 4 or 5 is used) from the location 140.3. As the system30 continues to scan, pixel elements P41-P44 are exposed on offsetlocations 140.41-140.44, respectively, shown in FIGS. 10.17-10.20,respectively. Pixel elements P41-P44 are on adjacent consecutive rowsR16, R17, R18, R19 of column C4 of the pixel panel 38.

[0057] Point Array System and Method

[0058] Referring now to FIG. 11, in another embodiment of the presentinvention, the photolithography system 30 utilizes a unique optic system150 in addition to the lens system 40. The optic system 150 is discussedin detail in U.S. patent Ser. No. 09/480,796, which is herebyincorporated by reference. It is understood that the lens system 40 isadaptable to various components and requirements of the photolithographysystem 30, and one of ordinary skill in the art can select and positionlenses appropriately. For the sake of example, a group of lenses 40 aand an additional lens 40 b are configured with the optic system 150.

[0059] The optic system 150 includes a grating 152 and a point array154. The grating 152 may be a conventional shadow mask device that isused to eliminate and/or reduce certain bandwidths of light and/ordiffractions between individual pixels of the pixel panel 38. Thegrating 152 may take on various forms, and in some embodiments, may bereplaced with another device or not used at all.

[0060] The point array 154 is a multi-focus device. There are many typesof point arrays, including a Fresnel ring, a magnetic e-beam lens, anx-ray controlled lens, and an ultrasonic controlled light condensationdevice for a solid transparent material.

[0061] In the present embodiment, the point array 154 is a compilationof individual microlenses, or microlens array. In the presentembodiments, there are as many individual microlenses as there are pixelelements in the pixel panel 38. For example, if the pixel panel 38 is aDMD with 600×800 pixels, then the microlens array 154 may have 600×800microlenses. In other embodiments, the number of lenses may be differentfrom the number of pixel elements in the pixel panel 38. In theseembodiments, a single microlens may accommodate multiple pixels elementsof the DMD, or the pixel elements can be modified to account foralignment. For the sake of simplicity, only one row of four individuallenses 154 a, 154 b, 154 c, 154 d will be illustrated. In the presentembodiment, each of the individual lenses 154 a, 154 b, 154 c, 154 d isin the shape of a rain drop. This shape provides specific diffractionbenefits that will be discussed below. It is understood, however, thatshapes other than those illustrated may also be used.

[0062] Similar to the lens system 40 of FIG. 1, the optic system 150 isplaced between the pixel panel 38 and the subject 42. For the sake ofexample, in the present embodiment, if the pixel panel 38 is a DMDdevice, light will (selectively) reflect from the DMD device and towardsthe optic system 150. If the pixel panel 38 is a LCD device, light will(selectively) flow through the LCD device and towards the optic system150. To further exemplify the present embodiment, the pixel panel 38includes one row of elements (either mirrors or liquid crystals) forgenerating four pixel elements.

[0063] In continuance with the example, four different pixel elements156 a, 156 b, 156 c, 156 d are projected from each of the pixels of thepixel panel 38. In actuality, the pixel elements 156 a, 156 b, 156 c,156 d are light beams that may be either ON or OFF at any particularinstant (meaning the light beams exist or not, according to thepixel-mask pattern), but for the sake of discussion all the light beamsare illustrated.

[0064] The pixel elements 156 a, 156 b, 156 c, 156 d pass through thelens system 40 a and are manipulated as required by the currentoperating conditions. As discussed earlier, the use of the lens system40 a and 40 b are design options that are well understood in the art,and one or both may not exist in some embodiments. The pixel elements156 a, 156 b, 156 c, 156 d that are manipulated by the lens system 40 aare designated 158 a, 158 b, 158 c, 158 d, respectively.

[0065] The pixel elements 158 a, 158 b, 158 c, 158 d then pass throughthe microlens array 154, with each beam being directed to a specificmicrolens 154 a, 154 b, 154 c, 154 d, respectively. The pixel elements158 a, 158 b, 158 c, 158 d that are manipulated by the microlens array154 are designated as individually focused light beams 160 a, 160 b, 160c, 160 d, respectively. As illustrated in FIG. 11, each of the lightbeams 160 a, 160 b, 160 c, 160 d are being focused to focal points 162a, 162 b, 162 c, 162 d for each pixel element. That is, each pixelelement from the pixel panel 38 is manipulated until it focuses to aspecific focal point. It is desired that the focal points 162 a, 162 b,162 c, 162 d exist on the subject 42. To achieve this goal, the lens 40b may be used in some embodiments to refocus the beams 160 a, 160 b, 160c, 160 d on the subject 42. FIG. 11 illustrates focal points 162 a, 162b, 162 c, 162 d as singular rays, it being understood that the rays maynot indeed be focused (with the possibility of intermediate focalpoints, not shown) until they reach the subject 42.

[0066] Continuing with the present example, the subject 42 includes fourexposure sites 170 a, 170 b, 170 c, 170 d. The sites 170 a, 170 b, 170c, 170 d are directly associated with the light beams 162 a, 162 b, 162c, 162 d, respectively, from the microlenses 154 a, 154 b, 154 c, 154 d,respectively. Also, each of the sites 170 a, 170 b, 170 c, 170 d areexposed simultaneously. However, the entirety of each site 170 a, 170 b,170 c, 170 d is not exposed at the same time.

[0067] Referring now to FIG. 12, the maskless photolithography system 30with the optic system 150 can also performs two-dimensional digitalscanning, as discussed above with reference to FIG. 8. For example, theimage from the pixel panel 38 may be aligned at the angle

(equations 2 and 3, above) with the scan direction 136.

[0068] Referring also to FIGS. 13, the present embodiment works verysimilar to the embodiments of FIGS. 9-10. However, instead of arelatively large location being exposed, the pixel elements are focusedand exposed to a relatively small point (e.g., individually focusedlight beams 162 a, 162 b, 162 c, 162 d from FIG. 11) on the sites 170 a,170 b, 170 c, 170 d.

[0069] First of all, the pixel element 156 a exposes the individuallyfocused light beam 162 a onto the single site 170 a of the subject 42.The focused light beam 162 a produces an exposed (or unexposed,depending on whether the pixel element 156 a is ON or OFF) focal pointPT1. As the system 30 scans, pixel element 156 b exposes theindividually focused light beam 162 b onto the site 170 a. The focusedlight beam 162 b produces an exposed (or unexposed) focal point PT2.Focal point PT2 is slightly offset from the focal point PT1 in the ydirection (or −y direction). As the system 30 continues to scan, pixelelements 156 c and 156 d expose the individually focused light beams 162c and 162 d, respectively, onto the site 170 a. The focused light beams162 c and 162 d produce exposed (or unexposed) focal points PT3 and PT4,respectively. Focal point PT3 is slightly offset from the focal pointPT2 in the y direction (or −y direction), and focal point PT4 issimilarly offset from the focal point PT3.

[0070] Once N pixel elements have been projected, the next pixels beingprojected onto the desired sites are of an adjacent column. Thisoperation is similar to that shown in FIGS. 10.6-10.20. The aboveprocess repeats to fully scan the desired overlapped image on the site170 a.

[0071] It is understood that while light beam 162 a is being exposed onthe site 170 a, light beam 162 b is being exposed on the site 170 b,light beam 162 c is being exposed on the site 170 c, and light beam 162d is being exposed on the site 170 d. Once the system 30 scans one time,light beam 162 a is exposed onto a new site (not shown), while lightbeam 162 b is exposed on the site 170 a, light beam 162 c is exposed onthe site 170 b, and light beam 162 d is exposed on the site 170 c. Thisrepeats so that the entire subject can be scanned (in the y direction)by the pixel panel 38.

[0072] It is further understood that in some embodiments, the subject 42may be moved rapidly while the light beams (e.g., 162 a-d) transitionfrom one site to the other (e.g., 170 a-170 d, respectively), and slowlywhile the light beams are exposing their corresponding sites.

[0073] By grouping several pixel panels together in the x-direction, theentire subject can be scanned by the pixel panels. The computer system36 can keep track of all the data provided to each pixel panel toaccommodate the entire scanning procedure. In other embodiments, acombination of scanning and stepping can be performed. For example, ifthe subject 42 is a wafer, a single die (or group of die) can bescanned, and then the entire system 30 can step to the next die (or nextgroup).

[0074] The example of FIGS. 11-13 are limited in the number of pixelelements for the sake of clarity. In the figures, each focal point has adiameter of about 2 the length l or width w of the site 170 a. Since N=4in this example, the overlap spacing is relatively large and the focalpoints do not overlap very much, if at all. As the number of pixelelements increase (and thus N increases), the resolution and amount ofoverlapping increase, accordingly.

[0075] For further example, FIG. 14 illustrates a site 220 that has beenexposed by 600 pixel elements with focal points PT1-PT600 (e.g., from a600×800 DMD). As can be seen, the focal points PT1-PT600 are arranged inan array (similar to equation 1, above) of:

(M,N)=20 focal points×30 focal points.   (6)

[0076] By selectively turning ON and OFF the corresponding pixelelements, a plurality of structures 222, 224, 226 can be formed on thesite 220. It is noted that structures 222-226 have good resolution andcan be drawn to various different shapes, including diagonal. It isfurther noted that many of the focal points on the periphery of the site220 will eventually overlap with focal points on adjacent sites. Assuch, the entire subject 42 can be covered by these sites.

[0077] Alternatively, certain focal points or other types of exposedsites can be overlapped to provide sufficient redundancy in the pixelpanel 38. For example, the same 600 focal points of FIG. 14 can be usedto produce an array of:

(M,N)=20 focal points×15 focal points.   (7)

[0078] By duplicating the exposure of each focal point, this redundancycan accommodate one or more failing pixel elements in the pixel panel38.

[0079] Scaling

[0080] Referring now to FIG. 15, as discussed above, the pixel panel 38may be rotated by an angle with respect to the subject 42 (angle θ, FIG.8). This rotation is also described in U.S. Ser. No. 09/923,233,entitled “Real Time Data Conversion For A Digital Display” filed on Aug.3, 2001, also assigned to Ball Semiconductor, Inc., and herebyincorporated by reference as if reproduced in its entirety. The pixelpanel 38 scans the subject 42 in a direction indicated by an arrow 232at a certain speed or “scan rate.”

[0081] Often, it is desirable to scale an image that is being exposedonto a subject. For example, if the subject is a flexible member, suchas a textile, the image being exposed may need to be scaled toaccommodate changes in the subject. Scaling may be performed vertically(in the direction of the arrow 232), horizontally (perpendicular to thearrow 232) or a combination of the two.

[0082] In one embodiment, vertical scaling may be achieved by adjustingthe scan rate in relation to the frequency of the projected light. Ifthe desired adjustment is less than the wavelength of the light, anoptical interferometer position measurement system may be needed.

[0083] Horizontal scaling may also be achieved by “relocating” the datafor the pixel element to a different pixel element that aligns with thefocal point 234. The location of the different pixel element can bedetermined by recalculating the data locations on the pixel panel 38.This recalculation can be performed, for example, by the computer system36 (FIG. 1). It is understood that the effectiveness of such arecalculation depends on whether the distance D is divisible by aspacing between two focal points. For example, if the focal point 234 isonly one half of a pixel away from the current focal point 230, then a“closest” pixel element must be determined.

[0084] Referring generally to FIGS. 16, 17a, and 17 b, in oneembodiment, a method 300 can be used to scale the original focal point230 to the scaled focal point 234. The method can be performed, forexample, by the computer system 36 (FIG. 1), or a secondary computer.

[0085] A pixel element (not shown) is to be scaled for projection ontothe subject 42 by the pixel panel 38. The pixel element is representedby three focal points 230 (the original focal point), 242 (the rotatedfocal point), and 234 (the scaled focal point), each of will bedescribed in greater detail. Before scaling, the alignment and scan rateof the pixel panel 38 with respect to the subject 42 would be operableto project the pixel element onto the focal point 230. However, thepixel element is to be horizontally scaled by a distance “D” from thefocal point 230 to the focal point 234 before projection.

[0086] To achieve this horizontal scaling, the method 300 begins withcalculating the site of the focal point 230 in step 302 and an originalangle of rotation θ_(OS) of the pixel panel 38 relative to the subject42 in step 304. The site of the focal point 230 is calculated in step306 and a new angle of rotation θ_(NS) of the pixel panel 38 relative tothe subject 42 is calculated in step 308. The angle θ_(NS) defines theangle to which the pixel panel should be rotated in order to align thepixel element with the focal point 242, which is horizontally alignedwith the focal point 234. The pixel panel 38 is then rotated in step 310to coincide with the angle θ_(NS), which aligns the pixel element withthe rotated focal point 242. To vertically align the pixel element withfocal point 234, the scan rate of the pixel panel 38 relative to thesubject 42 may be altered in step 312.

[0087] Referring now specifically to FIGS. 17a and 17 b, the pixel panel38 is originally aligned in a rotated position 246 relative to thesubject 42. The pixel element may be referenced with respect to thepixel panel 38 using a two dimensional coordinate system (the pixelpanel coordinate system) comprising an x-axis X_(DMD) parallel with thetop and bottom edges of the pixel panel 38, and a y-axis Y_(DMD)parallel with the left and right edges of the pixel panel 38. The pixelpanel 38 is scanned relative to the subject 42 in a direction 248 whichis substantially parallel to the y-axis Y_(DMD). The angle of rotationbetween the original rotated position 248 and the subject 42 is denotedby θ_(OS).

[0088] The pixel element may be referenced with respect to the subject42 using a second two dimensional coordinate system (the subjectcoordinate system) comprising an x-axis X_(S) parallel with the top andbottom edges of the subject 42, and a y-axis Y_(S) parallel with theleft and right edges of the subject 42. Utilizing the pixel panel andsubject coordinate systems enables the calculation of various aspects ofthe focal points 230, 234.

[0089] The original focal point 230 may be calculated in the subjectcoordinate system using the equations:

X _(S) =X _(DMD)*cos(θ_(OS))+Y _(DMD)*sin(θ_(OS));   (8)

Y _(S) =X _(DMD)*sin(θ_(OS))−Y _(DMD)*cos(θ_(OS)).   (9)

[0090] Horizontally shifting the pixel element the distance D from thefocal point 230 to the focal point 234 is accomplished by first rotatingthe pixel panel 38. In the present illustration, this rotation occurs ina clockwise manner. Before the rotation occurs, the coordinates of thedesired focal point 234 and a new angle of rotation θ_(NS) between thepixel panel 38 and the subject 42 may be calculated in the subjectcoordinate system using the equations:

D=X _(DMD)*(cos(θ_(NS))−cos(θ_(OS)));   (10)

X _(S) =X _(DMD)*cos(θ_(NS))+Y_(DMD)*sin(θ_(NS));   (11)

Y _(S) =X _(DMD)*sin(θ)−Y _(DMD)*cos(θ_(NS)).   (12)

[0091] Accordingly, the pixel panel 38 can be rotated through an angleθ_(DIFF), which may be calculated as the difference between θ_(OS) andθ_(NS) or, in equation form,

θ_(DIFF)=θ_(OS)−θ_(NS)   (13)

[0092] Therefore, rotating the pixel panel 38 in a clockwise directionthrough the angle θ_(DIFF) will position the pixel panel at the position250. Accordingly, the pixel element will be projected onto the rotatedfocal point 242. As described previously, the focal point 242 ishorizontally aligned with the desired focal point 234, but is notvertically aligned. Vertical alignment may be achieved by altering thescan rate of the pixel panel 38 relative to the subject 42. The verticaldistance between the focal point 242 and the focal point 234 may becalculated in a manner using the pixel panel and subject coordinatesystems as previously described. This enables vertical alignment of thepixel element and completes the scaling process.

[0093] Referring now to FIGS. 18 and 19, in another embodiment, thepixel panel 38 is moving relative to the subject 42 in a direction 252.The pixel panel 38 is to project a pixel element (not shown) onto afocal point 254. However, the focal point 254 is inaccessible to thepixel panel 38 as illustrated in FIG. 18, where the focal point 254 is adistance “D” away from the pixel panel 38. Such inaccessibility may becaused, for example, by the pixel panel's alignment relative to thesubject 42, by the expansion or contraction of the subject 42, or by acombination of these and/or other factors.

[0094] To properly project the pixel element onto the focal point 254,the pixel panel 38 may be moved so that its projection area includes thefocal point 254. This may be accomplished by calculating coordinates forthe focal point 254 using coordinate systems relative to the pixel panel38 and/or the subject 42. Such calculations may be accomplished asdescribed in reference to FIGS. 16 and 17. For example, the originallocation 230 and the scaled location 234 discussed with FIGS. 16 and 17may be a particular pixel of the pixel panel 38 and the focal point 234,respectively. Once the calculations are complete, the pixel panel 38 maybe rotated so as to encompass the focal point 234 as illustrated in FIG.19.

[0095] While the invention has been particularly shown and describedwith reference to the preferred embodiment thereof, it will beunderstood by those skilled in the art that various changes in form anddetail may be made therein without departing form the spirit and scopeof the invention. For example, the pixel panel 38 may be rotated in acounterclockwise manner to position the pixel element. In addition, apixel element may be vertically aligned prior to aligning ithorizontally. In some embodiments, certain calculations may be performedduring the rotation of the pixel panel 38 and/or alteration of the scanrate, while in other embodiments the calculations may be completedbefore any actual physical alignment is undertaken. Additionally, asingle coordinate system may be utilized for both the pixel panel 38 andthe subject 42. In other embodiments, the third angle may be omittedfrom the calculations. Therefore, the claims should be interpreted in abroad manner, consistent with the present invention.

What is claimed is:
 1. A method for scaling a pixel element on a subjectpositioned in a first plane, the method comprising: providing a pixelpanel to generate the pixel element, the pixel panel positioned in asecond plane substantially parallel to the first plane; determining afirst scan rate; determining an original focal point of the pixelelement on the subject; calculating a scaled focal point for the pixelelement on the subject, the scaled focal point including a firstcoordinate in a first dimension and a second coordinate in a seconddimension; rotating the pixel panel relative to the subject to positionthe pixel element at the first coordinate in the first dimension of thescaled focal point; and altering the first scan rate to a second scanrate to position the pixel element at the second coordinate in thesecond dimension of the scaled focal point.
 2. The method of claim 1further including identifying the first and second dimensions inrelation to a coordinate system.
 3. The method of claim 2 wherein thefirst dimension is perpendicular to a scan direction and the seconddimension is parallel to the scan direction.
 4. The method of claim 1further including calculating a first angle between the pixel panel andthe subject prior to the rotation.
 5. The method of claim 4 furtherincluding calculating a second angle defining the rotation of the pixelpanel, the calculation including: calculating a third angle between thepixel panel and the subject, the third angle operable to position thepixel element at the first coordinate in the first dimension of thescaled focal point; and determining a difference between the first angleand the third angle, the difference defining the second angle.
 6. Themethod of claim 1 wherein the scaled focal point is inaccessible to thepixel panel prior to the pixel panel's rotation.
 7. The method of claim1 further including: calculating a distance in the second dimension; andutilizing the distance in altering the specified rate.
 8. The method ofclaim 1 wherein the scaled focal point is not a pixel multiple of theoriginal focal point and so the pixel element cannot be positioned atthe scaled focal point by rearranging the pixel element on the pixelpanel.
 9. A method for selectively rotating a pixel panel to repositiona pixel element from a first site to a second site for projection onto asubject, the method comprising: calculating the first site for the pixelelement on the subject; calculating a first angle of rotation betweenthe pixel panel and the subject, the first angle operable to align thepixel element with the first site in a first dimension and a seconddimension; calculating the second site of the pixel element on thesubject; calculating a second angle of rotation between the pixel paneland the subject, the second angle operable to align the pixel elementwith the second site in the first dimension; rotating the pixel panelfrom the first angle to the second angle to align the pixel element withthe second site in the first dimension; and selectively moving the pixelpanel with respect to the subject to align the pixel element with thesecond site in the second dimension.
 10. The method of claim 9 furtherincluding determining an amount of rotation by calculating a thirdangle, the calculation including subtracting the second angle from thefirst angle.
 11. The method of claim 9 further including calculating avertical distance defining the selective movement in the seconddimension.
 12. The method of claim 9 wherein the second site is locatedoutside of the projection area of the pixel panel prior to the rotationof the pixel panel.
 13. The method of claim 9 wherein the location ofthe second site on the subject is not a multiple of the first site, andso is not accessible by repositioning the pixel element on the pixelpanel.
 14. A system for scaling a pixel element during photolithographicprocessing, the system comprising: a memory operable to store the pixelelement; a pixel panel operable to receive the pixel element from thememory and project the pixel element onto a subject; a processoroperable to rotate the pixel panel relative to the subject; and softwarestored in the memory, the software including instructions for: alteringthe relative positions of the pixel panel and the subject at a specifiedrate; determining an original location of the pixel element on thesubject; calculating a scaled location for the pixel element on thesubject, the scaled location including a first coordinate in a firstdimension and a second coordinate in a second dimension; rotating thepixel panel relative to the subject to position the pixel element at thefirst coordinate in the first dimension of the scaled location; andaltering the specified rate to position the pixel element at the secondcoordinate in the second dimension of the scaled location.
 15. Thesystem of claim 14 wherein the software further includes instructionsfor: calculating a second angle defining the rotation of the pixelpanel, the calculation including: calculating a third angle between thepixel panel and the subject, the third angle operable to position thepixel element at the first coordinate in the first dimension of thescaled location; and determining a difference between the first angleand the third angle, the difference defining the second angle.
 16. Thesystem of claim 14 wherein the software further includes instructionsfor: calculating a distance in the second dimension; and utilizing thedistance in altering the specified rate.